6$ Experiments on Charcoal. 



It appeared to u& of importance to make fome experiment* 

 on this fubjecr., and we propofui the following queuions : 



Does hydrogen exift in charcoal when properly made? 

 Are the various kinds of charcoal indebted for their differ- 

 ences to the quantities of oxygen winch they contain? 



We employed two methods to come to the folution of thefe 

 problems : the action of oxygen, and that of fulphur. 



First Method. 

 Aclion of Oocygen* 



In our memoir on the gafeous oxide of carbon we gave 

 an account of experiments on the combuftion of charcoal in 

 clofe veflels in which no water was depofited. It is, how- 

 ever, poilible that fome was produced, but that it became dif- 

 folved in the carbonic acid gas, in which a great difiulving 

 power is generally obferved. 



In repeating the combuftion of different kinds of charcoal 

 properly made, but of which fome remained expoied to the 

 air, we remarked that the latter fuffered a great deal of water 

 to evaporate merely by the aclion of the heat, and that during 

 their combuftion it was not produced in fufHcient quantity to 

 be deposited. Thofe which had been carefully protected from 

 the action of humidity exhibited no traces of it. 



This proved to us that the water obferved during the com- 

 buftion of charcoal previoufly exiited, and that it had been 

 taken up by that fubftance, the hygrometric property of 

 which, long known, has been confirmed by C. Guy ton, in 

 the Encyclopedic Methodique. 



We again aflured ourfelves that charcoal of white wood 

 well made *, weighing 4 grammes, by remaining expofed to 

 the atmofphere even during dry weather, increafed in weight 

 o*3 grammes. When heated, the water is expelled ; which 

 may be weighed, and which forms more than three-fourths 

 of that augmentation. The remainder is air, which may be 

 ■difengageu either by heat or by expolure of the charcoal in a 

 vacuum. It may be readily conceived that thefe phamomena, 

 which depend on the date of the atmofphere, the texture of 

 the charcoal, and the time of its expolure to the air, muft be 

 exceedingly variable. 



It is then certain that, if water is produced in the com- 

 buftion of charcoal, it can exili only in the ftate of vapour in 

 the gafes which refult from it. 



It became a matter of importance to know what quan- 

 tity of water thefe gafes might contain. M. de Saufiure 



'■■ Wc confidtr charcoal to be To, when, ufrtr a firfl carbonization, it has 

 been expoied for an hour to the adtion ©f a ftropg furnace. 



9 announces, 



